In this study, we analyzed a total of 2185 cases over the past 10 years, identifying 31 cases of TB infection with an incidence rate of 1.4%. A matched case-control analysis compared these cases to 31 non-TB controls from the same donor pool. While overall patient survival was similar between groups, TB patients experienced a significant decline in kidney function. Diabetes mellitus and hepatitis emerged as independent risk factors for post-transplant TB.
It has been reported that the incidence of tuberculosis after renal transplantation is 0.5%~3.2%[7]. In Brazil, an area with a high incidence of TB, a retrospective study reported an incidence of 1.17–5%[8]. In our study, the incidence of tuberculosis was 1.4%. The potential infection mechanisms include the reactivation of latent Mycobacterium tuberculosis infection, direct transmission from the donor, and de novo acquisition of Mycobacterium tuberculosis[9]. In addition, immunosuppressive therapy renders recipients susceptible to Mycobacterium tuberculosis, facilitating rapid progression to miliary TB upon exposure[10]. Therefore, more detailed tuberculosis screening of donors before transplantation is conducive to reducing the incidence of TB after transplantation.
Most patients were infected with TB within 1 year after surgery, with a median onset time of 11 months after surgery(IQR, 5–25), which may be related to latent reactivation of mycobacterium tuberculosis. Therefore, the possibility of TB infection should not be ignored when a patient presents with a lung infection in the early post-transplant period. It has been documented that the risk of TB recurrence in latent TB patients is 5% per year for the first 5 to 7 years, then decreases to 0.1% per year[11].Therefore, in the early period after transplantation, more vigilance should be paid to the occurrence of tuberculosis.
At the beginning of anti-tuberculosis treatment, the comparison of creatinine changes between the two groups at different time points showed that there were significant differences in creatinine and glomerular filtration rate between the two groups at the 3rd, 6th and 12th month, and the greater the difference was with statistical significance as the treatment time extended. There were significant changes in creatinine curve and glomerular filtration rate curve between the two groups (P = 0.004, P = 0.001). A retrospective study of kidney transplant recipients with active tuberculosis revealed a graft loss rate of 14.7%. Additionally, tuberculosis treatment was associated with acute kidney injury and a failure of graft function returning to pre-infection baseline levels[12]. Costa et al.[4] showed that tuberculosis is significantly associated with the incidence of acute kidney injury (AKI), and the severity of AKI is an important factor in determining the prognosis of transplanted kidney function. Studies by Viana et al. [5] show that about 25% of patients will experience graft loss after anti-TB treatment, and 20% of patients will stop taking the drug due to drug toxicity. Our study reported acute kidney injury, acute rejection, and graft loss in 6(19.35%), 3(9.68%), and 3(9.68%) cases, respectively, underscoring the critical need for close renal function monitoring and delicate immunosuppressant management in this patient population.
Rifampicin, an anti-tuberculosis medication, is known to interact significantly with immunosuppressive agents. By inducing both P-glycoprotein (P-gp) and cytochrome P450 3A4 (CYP3A4), rifampicin can substantially reduce the levels of calcineurin inhibitors, thereby increasing the risk of graft rejection during anti-tuberculosis therapy and potentially compromising renal function[13]. To maintain therapeutic levels of calcineurin inhibitors during post-transplant anti-tuberculosis treatment, a threefold dose increase is often required[1]. Therefore, meticulous immunosuppressant management and close drug level monitoring are essential during TB treatment to prevent AKI, rejection and graft loss.
Previous studies have shown that the mortality rate of kidney transplant patients infected with tuberculosis is 14.3%-31.9%, which is mainly related to the severity of tuberculosis and treatment complications[14]. Bodro et al. 's study of tuberculosis infection after transplantation also revealed a 17% mortality rate[15]. In this study, only one patient (3.2%) died following tuberculosis infection. Reviewing this case, we determined the cause of death to be respiratory failure secondary to severe pneumonia. Drug-induced hepatotoxicity developed after one week of treatment, as evidenced by elevated transaminase levels. Intermittent drug interruptions posed a risk of treatment failure and contributed to the fatal outcome. All 30 remaining patients with tuberculosis infection were successfully treated. The median treatment duration for the tuberculosis group was 8 months (IQR, 7–10). One of the 30 patients exhibited resistance to isoniazid and rifampicin. This patient underwent a 14-month treatment regimen with cycloserine, moxifloxacin, propylthioisamide, and linezolid, resulting in a successful cure. The mortality rate in our center was lower than reported in some studies. This may be attributed to our vigilance on TB infection and early diagnosis facilitated by advanced technologies such as NGS and TB PCR testing.
Multivariate logistic regression analysis identified diabetes mellitus (OR 11.03, 95% CI 2.03–59.85, p = 0.005) and hepatitis (OR 7.19, 95% CI 1.25–41.26, p = 0.027) as independent risk factors for TB infection, consistent with previous literature.[16, 17]. A meta-analysis of 13 observational studies revealed a two- to threefold increased risk of tuberculosis infection among individuals with diabetes[18]. Diabetes is a noncommunicable disease that can impair host immunity and lead to increased susceptibility to various infectious diseases, including tuberculosis[19].Diabetes impairs the innate response of TB patients to the initial TB infection, leading to delayed adaptive immune response, which is a key mechanism by which hyperglycemia contributes to TB susceptibility[20]. Strict glycemic control is crucial for preventing tuberculosis in transplant recipients. Previous studies have shown that compared with non-diabetic patients, diabetic patients may have lower interferon gamma release, and tuberculosis spot test has lower sensitivity in diabetic patients, which leads to delayed diagnosis of tuberculosis infection[21, 22]. Diabetes also has an important impact on the effectiveness of TB treatment[23]. TB patients with diabetes are also at increased risk for delayed sputum culture conversion, treatment failure, recurrence, and mortality [24].
Of the 9512 TB cases reported in New York City from 2000 to 2010, 350 (3.7%) TB cases were co-infected with chronic hepatitis, compared to 1.2% in the general population, demonstrating the close relationship between the two infectious diseases[25]. A large number of studies have shown that TB patients with hepatitis are more likely to develop liver dysfunction after receiving anti-TB therapy than TB patients without hepatitis[26, 27]. Given the increased risk of liver toxicity associated with anti-tuberculosis drugs, patients with hepatitis require particularly close monitoring of liver function. Careful drug selection, dose adjustment, and timely intervention, including drug cessation and liver protective measures, are essential to prevent adverse outcomes[28].
This study has several limitations. The relatively small sample size restricted the statistical power of our analyses. Moreover, the two-year follow-up period may have underestimated long-term outcomes. Future research should incorporate immunosuppressive drug levels to elucidate their role on balancing TB treatment and graft survival.
In conclusion, our study highlights the significant impact of tuberculosis (TB) on kidney transplant recipients, emphasizing the importance of early detection and comprehensive management. While standard anti-TB treatment is effective, the risk of kidney dysfunction necessitates close monitoring and tailored immunosuppression strategies. Identifying diabetes mellitus and hepatitis as independent risk factors underscores the need for targeted preventive interventions in high-risk populations. Further research with larger sample sizes and extended follow-up periods is warranted to refine our understanding of post-transplant TB and optimize patient outcomes.